Explosive coating material



Patented Sept. 11, 1934 EXPLOSIVE COATING MATERIAL Norman G. Johnson and Harold A. Lewis, VVoodbury, N. J., assignors to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing. Application April 21, 1933,

Serial No. 667,230

11 Claims.

This invention relates to explosive compositions and more particularly to an ingredient of such compositions, said ingredient being coated with an organic explosive compound in such a manner as to impart highly improved properties to the explosive compositions.

The commercial high explosives in use at the present time consist for the most part of dynamites containing nitroglycerin as the principal sensitive explosive ingredient. These explosives have retained their dominant position over a period of many years, since no other explosive material has been available having the generally excellent properties of nitroglycerin, namely, those of stability, uniformity of action, high sensitizing power, and favorable oxygen balance.

There has been one ,disadvantage in the use of' nitroglycerin, however, in that it causes severe headaches to the persons coming in contact with 0 it. and with explosives containing it, or to those inhaling its vapors. This unfavorable physiological property has not been peculiar to nitroglycerin alone, but has been common to'all liquid aliphatic nitric esters.

isfactory high explosive compositions containing no liquid ingredient, since such compositions would not cause the undesirable physiological effects that result from nitroglycerin explosives.

0 Nitrostarch powders are examples of such compositions and have been employed to some degree in blasting practice in America. These explosives, however, have not given thorough satisfaction, since they have had some outstanding dis- 5 advantages over nitroglycerin dynamites. One such disadvantage has been that nitrostarch is relatively insensitive to detonation, so that, in spite of the high velocity of the compound, the explosives may fail to propagate the explosion,

0 if the differentcartridges in the column are separated from one another in the bore hole by small amounts of dirt. rock, and the like. The occurrence of misfires from such a cause is a source of danger that must be guarded against very care- 5 fully, since any failed portion of the explosive must subsequently be removed from the bore hole, an operation that involves considerable hazard.

In addition to the sensitizing nitric ester, it is customary frequently to employ ammonium ni- 0 trate as an ingredient ofdynamites, since this salt is economically available and possesses high explosive strength when used with sensitizing materials capable of bringing it to detonation with maximum effectiveness. Ammonium ni- 5 trate is valuablealso as an oxidizing agentin the Various attempts have been made to make sat-' presence of oxygen-deficient materials, besides being itself an explosive compound. Its presence as an explosive ingredient, however, makes the problem of satisfactory sensitizing even more important.

The object of our invention is a high explosive composition free from toxic and headache-mo ducing effects. 'A-further object is such an explosive having a satisfactorily high degree of sensitiveness to detonation and propagation of the explosive wave. A still further object is an ammonium nitrate explosive containing no nitroglycerin, but being suificiently sensitive for effective use., Additional objects will be disclosed as the invention is further described.

We have found that the foregoing objects are attained when the dynamite composition contains one or more ingredients coated with pentaerythritol tetranitrate. As such an ingredient for coating, we prefer to use ammonium nitrate. The presence of pentaerythritol tetranitrate on the surface of the ammonium nitrate has the particular advantage of imparting sensitiveness to the ammonium nitrate particles andbringing about a more generally satisfactory explosive composition. The coating of pentaerythritol tetranitrate has the further advantage of lending water resistance to the ammonium nitrate.

While a satisfactory explosive composition, according to our invention, may be produced in which the pentaerythritol tetrahitrate used as the coating on the ammonium nitrate or other ingredient is the chief sensitizing agent, we may also include additional pentaerythritol tetranitrate in the composition beyond that present as coating material. In place of this additional pentaerythritol tetranitrate, we may use some other solid organic explosive compound. As such additional sensitizing material, we prefer to use nitrostarch. Various other explosive compounds, however, may be employed in like capacity, such as nitrocellulose, trinitrotoluene, and many others. The coating of pentaerythritol tetranitrate may similarly be applied to organic and inorganic explosive ingredients other than ammonium nitrate, particularly'those havng an oxidizing effect. Ammonium perchlorate is an explosive substance, for example, which may desirably be coated with pentaerythritol tetranitrate. Sodium nitrate also may be so coat-ed if desired, as well as many other compounds. It will be understood, of course, that uncoated sodium nitrate may be included as an ingredient in our composi- .tions.. Furthermore, in some cases, we may prefer to impregnate the explosive composition with pentaerythritol tetranitrate.

Nitrostarch is an amorphous substance and tends, therefore, to be of a fine, dusty nature.

6 For thisreasofi, it is desirable to use a small percentage 'of. a liquid ingredient in compositions containing nitrostarch, ,as well as in other compositions containing finely dividedsolid explosives. Engine oil, or other similar oil, .is advantageous for use in compositions according to our invention, and its presence tends to reduce the hazards during the mixing and handling of the explosive. I

As illustrative examples of an explosive composition according to our invention, the following are given: v

Pentaerythritol tetranitrate has an advantage for coating ammonium nitrate and other oxidizing agents over other materials that might suggest themselves for the purpose. Trinitrotoluene,

for example, is a compound that might be used in 'such capacity. The latter compound, however, is very deficient in oxygen, whereas pentaerythritol tetranitrate is deficient to a much less degree. When pentaerythritol tetranitrate is used, therefore, smaller amounts of oxidizing agents other than ammonium nitrate are required in order to obtain an explosive giving satisfactory products of combustion. Pentaerythritol tetranitrate has the advantage over TNT also of.

, a higher degree of sensitiveness, whereby the desired sensitizing effect is obtained with a smaller percentage of coating material or a greater effect is obtained by'the use of the same amount.

The relatively high melting point of pentaerythritol tetranitrate makes it undesirable to apply as a coating material in fused form. Prefer ably it will be applied in solution as a sprayed coating. More uniform results may be obtained in this manner. The use of acetone solutions of pentaerythritol tetranitrate for such purpose has been found satisfactory. While the amount of pentaerythritol tetranitrate present on the surface of the ammonium nitrate particles may vary widely, a satisfactory amount will be 10% by weight of the ammonium nitrate.

While our invention has been described in ;detail in the foregoing description, it will be understood that many departures may be made both in the ingredients used and in the amounts. It will be understood that all the common ingredients of dynamite compositions may be included in our compositions. We intend therefore to be limited only as indicated in the following patent claims:

We claim:

1. A new composition of matter, comprising an inorganic explosive salt coated with a composition consisting at least in part of pentaerythritol tetranitrate.

2. A new composition of matter, comprising ammonium perchlorate coated with pentaerythritol tetranitrate.

3. A new composition of matter, comprising ammonium nitrate coated with pentaerythritol tetranitrate.

4. A high explosive composition containing an 1 inorganic oxidizing agent coated with a composiinorganic explosive salt coated with pentaerythritol tetranitrate.

5. A high explosive composition containing an 6. A high explosive composition containing ammonium perchlorate coated with pentaerythritol tetranitrate. I

'7. A high explosive composition containing am- 1 monium nitrate coated with pentaerythritol tetranitrate. I

8. A high explosive composition, comprising an inorganic explosive salt coated with pentaerythritol tetranitrate, and an explosive sensitiz- 1 ing agent.

9. A high explosive composition, comprising ammonium nitrate coated with a composition consisting at least in part of pentaerythritol tetranitrate, and a solid organic explosive compound 1 as a sensitizing agent.

10. A-high explosive composition, comprising ammonium nitrate coated with pentaerythritol tetranitrate, and nitrostarch.

11. An inorganic explosive salt sensitized by 1 means of adherent pentaerythritol tetranitrate.

NORMAN G. JOHNSON. HAROLD\A. LEWIS.

CERTIFICATE OF CORRECTIONJ Patent No. 1,972,938.

Septeniher 11, 1934.

NORMAN G. JOHNSON, ET AL.

l t is hereby certified :that error appears in the printed'specification of the above numbered patent requiring correction as follows:

"inorganic-explosive salt coated with" and 4, strike out the words Page 2, line 102, claim insert the syllable and words tion consisting at least in part of; and that the said Letters Patent should be read'with this correction therein that the same may, conform to the record ot the casein the Patent Office.

Signed and sealed this 13th day of November, A. D.

stay Leslie Frazer Acting Commissioner of Patents. 

